Chapter 12 - Section 2 Measuring Earthquakes

WHAT WE KNOW… ____________________ are the shaking of Earth’s crust caused by _____________________________as lithospheric plates shift Focus: the point _______________where seismic activity begins Epicenter: the point _____________________directly above the focus.

LOCATING AN EPICENTER Use triangulation: Data from 3 different seismograph stations Look at ___________________________(time difference) between the arrival of ____ waves and ____ waves The ___________the lag time between P & S waves the ____________ you are from the earthquake’s ______________.

MAGNITUDE ___________ or amount of _____________released It is a measure of the amount of ___________________ Measured using the _________________________

Richter Scale Measures the ______________________ of an earthquake on a ___________________ Richter magnitude is determined by measuring the largest amplitude (wave height) recorded on the seismogram.

RICHTER SCALE Each increase in _____ on the Richter Scale represents a _____ fold increase in the wave magnitude.

INTENSITY A measure of the __________________ of an earthquake, uses the ______________________ Dependent on: 1. magnitude of earthquake 2. distance from epicenter 3. type of rock underlying region 4. ____________________________________________ Varies for each event

MERCALLI SCALE Mercalli Scale Description of what happened ___________________________ XII total destruction Not a true indication of the actual strength of an earthquake

MERCALLI SCALE

Magnitude vs. Intensity Would be possible for an earthquake in two locations to have the same MAGNITUDE on the Richter Scale but a different INTENSITY on the Mercalli Scale? Why or why not?

Richter and Mercalli Scales